Absolute quantitation of I-131 activity distributions using a high-resolution rotating collimator: a phantom study

The authors acquired SPECT data using a high-resolution rotating parallel-hole collimator especially designed for imaging of medium-energy radionuclides. They reconstructed images of I-131 activity distributions for a sphere inside a water-filled cylinder. Reconstructions were performed using FBP and iterative MAP/ICD methods. The MAP/ICD reconstructions with an edge-preserving convex prior provided the more accurate absolute activity distributions with better resolution (FWHM of 0.5 cm). The sphere´s activity and activity density were reproduced to within 5% of their known values